[exim.git] / doc / doc-txt / pcretest.txt

This file contains the PCRE man page that described the pcretest program. Note 
that not all of the features of PCRE are available in the limited version that 
is built with Exim.
-------------------------------------------------------------------------------

PCRETEST(1)                                                        PCRETEST(1)


NAME
       pcretest - a program for testing Perl-compatible regular expressions.

SYNOPSIS

       pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]
            [destination]

       pcretest  was written as a test program for the PCRE regular expression
       library itself, but it can also be used for experimenting with  regular
       expressions.  This document describes the features of the test program;
       for details of the regular expressions themselves, see the  pcrepattern
       documentation. For details of the PCRE library function calls and their
       options, see the pcreapi documentation.


OPTIONS

       -C        Output the version number of the PCRE library, and all avail-
                 able   information  about  the  optional  features  that  are
                 included, and then exit.

       -d        Behave as if each regex had  the  /D  (debug)  modifier;  the
                 internal form is output after compilation.

       -i        Behave  as  if  each  regex  had the /I modifier; information
                 about the compiled pattern is given after compilation.

       -m        Output the size of each compiled pattern after  it  has  been
                 compiled.  This  is  equivalent  to adding /M to each regular
                 expression.  For  compatibility  with  earlier  versions   of
                 pcretest, -s is a synonym for -m.

       -o osize  Set  the number of elements in the output vector that is used
                 when calling pcre_exec() to be osize. The  default  value  is
                 45, which is enough for 14 capturing subexpressions. The vec-
                 tor size can be changed  for  individual  matching  calls  by
                 including \O in the data line (see below).

       -p        Behave  as  if  each regex has /P modifier; the POSIX wrapper
                 API is used to call PCRE. None of the other options  has  any
                 effect when -p is set.

       -t        Run  each  compile, study, and match many times with a timer,
                 and output resulting time per compile or match (in  millisec-
                 onds).  Do  not set -m with -t, because you will then get the
                 size output a zillion times, and  the  timing  will  be  dis-
                 torted.


DESCRIPTION

       If  pcretest  is  given two filename arguments, it reads from the first
       and writes to the second. If it is given only one filename argument, it
       reads  from  that  file  and writes to stdout. Otherwise, it reads from
       stdin and writes to stdout, and prompts for each line of  input,  using
       "re>" to prompt for regular expressions, and "data>" to prompt for data
       lines.

       The program handles any number of sets of input on a single input file.
       Each  set starts with a regular expression, and continues with any num-
       ber of data lines to be matched against the pattern.

       Each data line is matched separately and independently. If you want  to
       do  multiple-line  matches, you have to use the \n escape sequence in a
       single line of input to encode  the  newline  characters.  The  maximum
       length of data line is 30,000 characters.

       An  empty  line signals the end of the data lines, at which point a new
       regular expression is read. The regular expressions are given  enclosed
       in any non-alphanumeric delimiters other than backslash, for example

         /(a|bc)x+yz/

       White  space before the initial delimiter is ignored. A regular expres-
       sion may be continued over several input lines, in which case the  new-
       line  characters  are included within it. It is possible to include the
       delimiter within the pattern by escaping it, for example

         /abc\/def/

       If you do so, the escape and the delimiter form part  of  the  pattern,
       but  since delimiters are always non-alphanumeric, this does not affect
       its interpretation.  If the terminating delimiter is  immediately  fol-
       lowed by a backslash, for example,

         /abc/\

       then  a  backslash  is added to the end of the pattern. This is done to
       provide a way of testing the error condition that arises if  a  pattern
       finishes with a backslash, because

         /abc\/

       is  interpreted as the first line of a pattern that starts with "abc/",
       causing pcretest to read the next line as a continuation of the regular
       expression.


PATTERN MODIFIERS

       A  pattern may be followed by any number of modifiers, which are mostly
       single characters. Following Perl usage, these are  referred  to  below
       as,  for  example,  "the /i modifier", even though the delimiter of the
       pattern need not always be a slash, and no slash is used  when  writing
       modifiers.  Whitespace  may  appear between the final pattern delimiter
       and the first modifier, and between the modifiers themselves.

       The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
       PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
       pile() is called. These four modifier letters have the same  effect  as
       they do in Perl. For example:

         /caseless/i

       The following table shows additional modifiers for setting PCRE options
       that do not correspond to anything in Perl:

         /A    PCRE_ANCHORED
         /C    PCRE_AUTO_CALLOUT
         /E    PCRE_DOLLAR_ENDONLY
         /N    PCRE_NO_AUTO_CAPTURE
         /U    PCRE_UNGREEDY
         /X    PCRE_EXTRA

       Searching for all possible matches within each subject  string  can  be
       requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
       called again to search the remainder of the subject string. The differ-
       ence between /g and /G is that the former uses the startoffset argument
       to pcre_exec() to start searching at a  new  point  within  the  entire
       string  (which  is in effect what Perl does), whereas the latter passes
       over a shortened substring. This makes a  difference  to  the  matching
       process if the pattern begins with a lookbehind assertion (including \b
       or \B).

       If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
       string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
       flags set in order to search for another, non-empty, match at the  same
       point.   If  this  second  match fails, the start offset is advanced by
       one, and the normal match is retried. This imitates the way  Perl  han-
       dles such cases when using the /g modifier or the split() function.

       There are yet more modifiers for controlling the way pcretest operates.

       The /+ modifier requests that as well as outputting the substring  that
       matched  the  entire  pattern,  pcretest  should in addition output the
       remainder of the subject string. This is useful  for  tests  where  the
       subject contains multiple copies of the same substring.

       The  /L modifier must be followed directly by the name of a locale, for
       example,

         /pattern/Lfr_FR

       For this reason, it must be the last modifier. The given locale is set,
       pcre_maketables()  is called to build a set of character tables for the
       locale, and this is then passed to pcre_compile()  when  compiling  the
       regular  expression.  Without  an  /L  modifier,  NULL is passed as the
       tables pointer; that is, /L applies only to the expression on which  it
       appears.

       The  /I  modifier  requests  that pcretest output information about the
       compiled pattern (whether it is anchored, has a fixed first  character,
       and  so  on). It does this by calling pcre_fullinfo() after compiling a
       pattern. If the pattern is studied, the results of that are  also  out-
       put.

       The /D modifier is a PCRE debugging feature, which also assumes /I.  It
       causes the internal form of compiled regular expressions to  be  output
       after compilation. If the pattern was studied, the information returned
       is also output.

       The /F modifier causes pcretest to flip the byte order of the fields in
       the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
       facility is for testing the feature in PCRE that allows it  to  execute
       patterns that were compiled on a host with a different endianness. This
       feature is not available when the POSIX  interface  to  PCRE  is  being
       used,  that is, when the /P pattern modifier is specified. See also the
       section about saving and reloading compiled patterns below.

       The /S modifier causes pcre_study() to be called after  the  expression
       has been compiled, and the results used when the expression is matched.

       The /M modifier causes the size of memory block used to hold  the  com-
       piled pattern to be output.

       The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
       rather than its native API. When this  is  done,  all  other  modifiers
       except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
       and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
       PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.

       The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
       set.  This  turns on support for UTF-8 character handling in PCRE, pro-
       vided that it was compiled with this  support  enabled.  This  modifier
       also causes any non-printing characters in output strings to be printed
       using the \x{hh...} notation if they are valid UTF-8 sequences.

       If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
       pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
       checking of the string for UTF-8 validity.


DATA LINES

       Before each data line is passed to pcre_exec(),  leading  and  trailing
       whitespace  is  removed,  and it is then scanned for \ escapes. Some of
       these are pretty esoteric features, intended for checking out  some  of
       the  more  complicated features of PCRE. If you are just testing "ordi-
       nary" regular expressions, you probably don't need any  of  these.  The
       following escapes are recognized:

         \a         alarm (= BEL)
         \b         backspace
         \e         escape
         \f         formfeed
         \n         newline
         \r         carriage return
         \t         tab
         \v         vertical tab
         \nnn       octal character (up to 3 octal digits)
         \xhh       hexadecimal character (up to 2 hex digits)
         \x{hh...}  hexadecimal character, any number of digits
                      in UTF-8 mode
         \A         pass the PCRE_ANCHORED option to pcre_exec()
         \B         pass the PCRE_NOTBOL option to pcre_exec()
         \Cdd       call pcre_copy_substring() for substring dd
                      after a successful match (number less than 32)
         \Cname     call pcre_copy_named_substring() for substring
                      "name" after a successful match (name termin-
                      ated by next non alphanumeric character)
         \C+        show the current captured substrings at callout
                      time
         \C-        do not supply a callout function
         \C!n       return 1 instead of 0 when callout number n is
                      reached
         \C!n!m     return 1 instead of 0 when callout number n is
                      reached for the nth time
         \C*n       pass the number n (may be negative) as callout
                      data; this is used as the callout return value
         \Gdd       call pcre_get_substring() for substring dd
                      after a successful match (number less than 32)
         \Gname     call pcre_get_named_substring() for substring
                      "name" after a successful match (name termin-
                      ated by next non-alphanumeric character)
         \L         call pcre_get_substringlist() after a
                      successful match
         \M         discover the minimum MATCH_LIMIT setting
         \N         pass the PCRE_NOTEMPTY option to pcre_exec()
         \Odd       set the size of the output vector passed to
                      pcre_exec() to dd (any number of digits)
         \P         pass the PCRE_PARTIAL option to pcre_exec()
         \S         output details of memory get/free calls during matching
         \Z         pass the PCRE_NOTEOL option to pcre_exec()
         \?         pass the PCRE_NO_UTF8_CHECK option to
                      pcre_exec()
         \>dd       start the match at offset dd (any number of digits);
                      this sets the startoffset argument for pcre_exec()

       A  backslash  followed by anything else just escapes the anything else.
       If the very last character is a backslash, it is ignored. This gives  a
       way  of  passing  an empty line as data, since a real empty line termi-
       nates the data input.

       If \M is present, pcretest calls pcre_exec() several times,  with  dif-
       ferent  values  in  the match_limit field of the pcre_extra data struc-
       ture, until it finds the minimum number that is needed for  pcre_exec()
       to  complete.  This  number is a measure of the amount of recursion and
       backtracking that takes place, and checking it out can be  instructive.
       For  most  simple  matches, the number is quite small, but for patterns
       with very large numbers of matching possibilities, it can become  large
       very quickly with increasing length of subject string.

       When  \O  is  used, the value specified may be higher or lower than the
       size set by the -O command line option (or defaulted to 45); \O applies
       only to the call of pcre_exec() for the line in which it appears.

       If  the /P modifier was present on the pattern, causing the POSIX wrap-
       per API to be used, only \B and \Z have any effect, causing  REG_NOTBOL
       and REG_NOTEOL to be passed to regexec() respectively.

       The  use of \x{hh...} to represent UTF-8 characters is not dependent on
       the use of the /8 modifier on the pattern.  It  is  recognized  always.
       There  may  be  any number of hexadecimal digits inside the braces. The
       result is from one to six bytes, encoded according to the UTF-8  rules.


OUTPUT FROM PCRETEST

       When a match succeeds, pcretest outputs the list of captured substrings
       that pcre_exec() returns, starting with number 0 for  the  string  that
       matched the whole pattern. Otherwise, it outputs "No match" or "Partial
       match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-
       TIAL,  respectively, and otherwise the PCRE negative error number. Here
       is an example of an interactive pcretest run.

         $ pcretest
         PCRE version 5.00 07-Sep-2004

           re> /^abc(\d+)/
         data> abc123
          0: abc123
          1: 123
         data> xyz
         No match

       If the strings contain any non-printing characters, they are output  as
       \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
       the pattern. If the pattern has the /+ modifier, the  output  for  sub-
       string  0 is followed by the the rest of the subject string, identified
       by "0+" like this:

           re> /cat/+
         data> cataract
          0: cat
          0+ aract

       If the pattern has the /g or /G modifier,  the  results  of  successive
       matching attempts are output in sequence, like this:

           re> /\Bi(\w\w)/g
         data> Mississippi
          0: iss
          1: ss
          0: iss
          1: ss
          0: ipp
          1: pp

       "No match" is output only if the first match attempt fails.

       If  any  of the sequences \C, \G, or \L are present in a data line that
       is successfully matched, the substrings extracted  by  the  convenience
       functions are output with C, G, or L after the string number instead of
       a colon. This is in addition to the normal full list. The string length
       (that  is,  the return from the extraction function) is given in paren-
       theses after each string for \C and \G.

       Note that while patterns can be continued over several lines  (a  plain
       ">" prompt is used for continuations), data lines may not. However new-
       lines can be included in data by means of the \n escape.


CALLOUTS

       If the pattern contains any callout requests, pcretest's callout  func-
       tion  is  called  during  matching. By default, it displays the callout
       number, the start and current positions in  the  text  at  the  callout
       time, and the next pattern item to be tested. For example, the output

         --->pqrabcdef
           0    ^  ^     \d

       indicates  that  callout number 0 occurred for a match attempt starting
       at the fourth character of the subject string, when the pointer was  at
       the  seventh  character of the data, and when the next pattern item was
       \d. Just one circumflex is output if the start  and  current  positions
       are the same.

       Callouts numbered 255 are assumed to be automatic callouts, inserted as
       a result of the /C pattern modifier. In this case, instead  of  showing
       the  callout  number, the offset in the pattern, preceded by a plus, is
       output. For example:

           re> /\d?[A-E]\*/C
         data> E*
         --->E*
          +0 ^      \d?
          +3 ^      [A-E]
          +8 ^^     \*
         +10 ^ ^
          0: E*

       The callout function in pcretest returns zero (carry  on  matching)  by
       default, but you can use an \C item in a data line (as described above)
       to change this.

       Inserting callouts can be helpful when using pcretest to check  compli-
       cated  regular expressions. For further information about callouts, see
       the pcrecallout documentation.


SAVING AND RELOADING COMPILED PATTERNS

       The facilities described in this section are  not  available  when  the
       POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
       ifier is specified.

       When the POSIX interface is not in use, you can cause pcretest to write
       a  compiled  pattern to a file, by following the modifiers with > and a
       file name.  For example:

         /pattern/im >/some/file

       See the pcreprecompile documentation for a discussion about saving  and
       re-using compiled patterns.

       The  data  that  is  written  is  binary. The first eight bytes are the
       length of the compiled pattern data  followed  by  the  length  of  the
       optional  study  data,  each  written as four bytes in big-endian order
       (most significant byte first). If there is no study  data  (either  the
       pattern was not studied, or studying did not return any data), the sec-
       ond length is zero. The lengths are followed by an exact  copy  of  the
       compiled pattern. If there is additional study data, this follows imme-
       diately after the compiled pattern. After writing  the  file,  pcretest
       expects to read a new pattern.

       A saved pattern can be reloaded into pcretest by specifing < and a file
       name instead of a pattern. The name of the file must not  contain  a  <
       character,  as  otherwise pcretest will interpret the line as a pattern
       delimited by < characters.  For example:

          re> </some/file
         Compiled regex loaded from /some/file
         No study data

       When the pattern has been loaded, pcretest proceeds to read data  lines
       in the usual way.

       You  can copy a file written by pcretest to a different host and reload
       it there, even if the new host has opposite endianness to  the  one  on
       which  the pattern was compiled. For example, you can compile on an i86
       machine and run on a SPARC machine.

       File names for saving and reloading can be absolute  or  relative,  but
       note  that the shell facility of expanding a file name that starts with
       a tilde (~) is not available.

       The ability to save and reload files in pcretest is intended for  test-
       ing  and experimentation. It is not intended for production use because
       only a single pattern can be written to a file. Furthermore,  there  is
       no  facility  for  supplying  custom  character  tables  for use with a
       reloaded pattern. If the original  pattern  was  compiled  with  custom
       tables,  an  attempt to match a subject string using a reloaded pattern
       is likely to cause pcretest to crash.  Finally, if you attempt to  load
       a file that is not in the correct format, the result is undefined.


AUTHOR

       Philip Hazel <ph10@cam.ac.uk>
       University Computing Service,
       Cambridge CB2 3QG, England.

Last updated: 10 September 2004
Copyright (c) 1997-2004 University of Cambridge.
Commit	Line	Data
495ae4b0 PH	1	This file contains the PCRE man page that described the pcretest program. Note
	2	that not all of the features of PCRE are available in the limited version that
	3	is built with Exim.
	4	-------------------------------------------------------------------------------
	5
	6	PCRETEST(1) PCRETEST(1)
	7
	8
	9
	10	NAME
	11	pcretest - a program for testing Perl-compatible regular expressions.
	12
	13	SYNOPSIS
	14
	15	pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]
	16	[destination]
	17
	18	pcretest was written as a test program for the PCRE regular expression
	19	library itself, but it can also be used for experimenting with regular
	20	expressions. This document describes the features of the test program;
	21	for details of the regular expressions themselves, see the pcrepattern
	22	documentation. For details of the PCRE library function calls and their
	23	options, see the pcreapi documentation.
	24
	25
	26	OPTIONS
	27
	28	-C Output the version number of the PCRE library, and all avail-
	29	able information about the optional features that are
	30	included, and then exit.
	31
	32	-d Behave as if each regex had the /D (debug) modifier; the
	33	internal form is output after compilation.
	34
	35	-i Behave as if each regex had the /I modifier; information
	36	about the compiled pattern is given after compilation.
	37
	38	-m Output the size of each compiled pattern after it has been
	39	compiled. This is equivalent to adding /M to each regular
	40	expression. For compatibility with earlier versions of
	41	pcretest, -s is a synonym for -m.
	42
	43	-o osize Set the number of elements in the output vector that is used
	44	when calling pcre_exec() to be osize. The default value is
	45	45, which is enough for 14 capturing subexpressions. The vec-
	46	tor size can be changed for individual matching calls by
	47	including \O in the data line (see below).
	48
	49	-p Behave as if each regex has /P modifier; the POSIX wrapper
	50	API is used to call PCRE. None of the other options has any
	51	effect when -p is set.
	52
	53	-t Run each compile, study, and match many times with a timer,
	54	and output resulting time per compile or match (in millisec-
	55	onds). Do not set -m with -t, because you will then get the
	56	size output a zillion times, and the timing will be dis-
	57	torted.
	58
	59
	60	DESCRIPTION
	61
	62	If pcretest is given two filename arguments, it reads from the first
	63	and writes to the second. If it is given only one filename argument, it
	64	reads from that file and writes to stdout. Otherwise, it reads from
65	stdin and writes to stdout, and prompts for each line of input, using
66	"re>" to prompt for regular expressions, and "data>" to prompt for data
67	lines.
68
69	The program handles any number of sets of input on a single input file.
70	Each set starts with a regular expression, and continues with any num-
71	ber of data lines to be matched against the pattern.
72
73	Each data line is matched separately and independently. If you want to
74	do multiple-line matches, you have to use the \n escape sequence in a
75	single line of input to encode the newline characters. The maximum
76	length of data line is 30,000 characters.
77
78	An empty line signals the end of the data lines, at which point a new
79	regular expression is read. The regular expressions are given enclosed
80	in any non-alphanumeric delimiters other than backslash, for example
81
82	/(a\|bc)x+yz/
83
84	White space before the initial delimiter is ignored. A regular expres-
85	sion may be continued over several input lines, in which case the new-
86	line characters are included within it. It is possible to include the
87	delimiter within the pattern by escaping it, for example
88
89	/abc\/def/
90
91	If you do so, the escape and the delimiter form part of the pattern,
92	but since delimiters are always non-alphanumeric, this does not affect
93	its interpretation. If the terminating delimiter is immediately fol-
94	lowed by a backslash, for example,
95
96	/abc/\
97
98	then a backslash is added to the end of the pattern. This is done to
99	provide a way of testing the error condition that arises if a pattern
100	finishes with a backslash, because
101
102	/abc\/
103
104	is interpreted as the first line of a pattern that starts with "abc/",
105	causing pcretest to read the next line as a continuation of the regular
106	expression.
107
108
109	PATTERN MODIFIERS
110
111	A pattern may be followed by any number of modifiers, which are mostly
112	single characters. Following Perl usage, these are referred to below
113	as, for example, "the /i modifier", even though the delimiter of the
114	pattern need not always be a slash, and no slash is used when writing
115	modifiers. Whitespace may appear between the final pattern delimiter
116	and the first modifier, and between the modifiers themselves.
117
118	The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
119	PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
120	pile() is called. These four modifier letters have the same effect as
121	they do in Perl. For example:
122
123	/caseless/i
124
125	The following table shows additional modifiers for setting PCRE options
126	that do not correspond to anything in Perl:
127
128	/A PCRE_ANCHORED
129	/C PCRE_AUTO_CALLOUT
130	/E PCRE_DOLLAR_ENDONLY
131	/N PCRE_NO_AUTO_CAPTURE
132	/U PCRE_UNGREEDY
133	/X PCRE_EXTRA
134
135	Searching for all possible matches within each subject string can be
136	requested by the /g or /G modifier. After finding a match, PCRE is
137	called again to search the remainder of the subject string. The differ-
138	ence between /g and /G is that the former uses the startoffset argument
139	to pcre_exec() to start searching at a new point within the entire
140	string (which is in effect what Perl does), whereas the latter passes
141	over a shortened substring. This makes a difference to the matching
142	process if the pattern begins with a lookbehind assertion (including \b
143	or \B).
144
145	If any call to pcre_exec() in a /g or /G sequence matches an empty
146	string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
147	flags set in order to search for another, non-empty, match at the same
148	point. If this second match fails, the start offset is advanced by
149	one, and the normal match is retried. This imitates the way Perl han-
150	dles such cases when using the /g modifier or the split() function.
151
152	There are yet more modifiers for controlling the way pcretest operates.
153
154	The /+ modifier requests that as well as outputting the substring that
155	matched the entire pattern, pcretest should in addition output the
156	remainder of the subject string. This is useful for tests where the
157	subject contains multiple copies of the same substring.
158
159	The /L modifier must be followed directly by the name of a locale, for
160	example,
161
162	/pattern/Lfr_FR
163
164	For this reason, it must be the last modifier. The given locale is set,
165	pcre_maketables() is called to build a set of character tables for the
166	locale, and this is then passed to pcre_compile() when compiling the
167	regular expression. Without an /L modifier, NULL is passed as the
168	tables pointer; that is, /L applies only to the expression on which it
169	appears.
170
171	The /I modifier requests that pcretest output information about the
172	compiled pattern (whether it is anchored, has a fixed first character,
173	and so on). It does this by calling pcre_fullinfo() after compiling a
174	pattern. If the pattern is studied, the results of that are also out-
175	put.
176
177	The /D modifier is a PCRE debugging feature, which also assumes /I. It
178	causes the internal form of compiled regular expressions to be output
179	after compilation. If the pattern was studied, the information returned
180	is also output.
181
182	The /F modifier causes pcretest to flip the byte order of the fields in
183	the compiled pattern that contain 2-byte and 4-byte numbers. This
184	facility is for testing the feature in PCRE that allows it to execute
185	patterns that were compiled on a host with a different endianness. This
186	feature is not available when the POSIX interface to PCRE is being
187	used, that is, when the /P pattern modifier is specified. See also the
188	section about saving and reloading compiled patterns below.
189
190	The /S modifier causes pcre_study() to be called after the expression
191	has been compiled, and the results used when the expression is matched.
192
193	The /M modifier causes the size of memory block used to hold the com-
194	piled pattern to be output.
195
196	The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
197	rather than its native API. When this is done, all other modifiers
198	except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
199	and REG_NEWLINE is set if /m is present. The wrapper functions force
200	PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
201
202	The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
203	set. This turns on support for UTF-8 character handling in PCRE, pro-
204	vided that it was compiled with this support enabled. This modifier
205	also causes any non-printing characters in output strings to be printed
206	using the \x{hh...} notation if they are valid UTF-8 sequences.
207
208	If the /? modifier is used with /8, it causes pcretest to call
209	pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
210	checking of the string for UTF-8 validity.
211
212
213	DATA LINES
214
215	Before each data line is passed to pcre_exec(), leading and trailing
216	whitespace is removed, and it is then scanned for \ escapes. Some of
217	these are pretty esoteric features, intended for checking out some of
218	the more complicated features of PCRE. If you are just testing "ordi-
219	nary" regular expressions, you probably don't need any of these. The
220	following escapes are recognized:
221
222	\a alarm (= BEL)
223	\b backspace
224	\e escape
225	\f formfeed
226	\n newline
227	\r carriage return
228	\t tab
229	\v vertical tab
230	\nnn octal character (up to 3 octal digits)
231	\xhh hexadecimal character (up to 2 hex digits)
232	\x{hh...} hexadecimal character, any number of digits
233	in UTF-8 mode
234	\A pass the PCRE_ANCHORED option to pcre_exec()
235	\B pass the PCRE_NOTBOL option to pcre_exec()
236	\Cdd call pcre_copy_substring() for substring dd
237	after a successful match (number less than 32)
238	\Cname call pcre_copy_named_substring() for substring
239	"name" after a successful match (name termin-
240	ated by next non alphanumeric character)
241	\C+ show the current captured substrings at callout
242	time
243	\C- do not supply a callout function
244	\C!n return 1 instead of 0 when callout number n is
245	reached
246	\C!n!m return 1 instead of 0 when callout number n is
247	reached for the nth time
248	\C*n pass the number n (may be negative) as callout
249	data; this is used as the callout return value
250	\Gdd call pcre_get_substring() for substring dd
251	after a successful match (number less than 32)
252	\Gname call pcre_get_named_substring() for substring
253	"name" after a successful match (name termin-
254	ated by next non-alphanumeric character)
255	\L call pcre_get_substringlist() after a
256	successful match
257	\M discover the minimum MATCH_LIMIT setting
258	\N pass the PCRE_NOTEMPTY option to pcre_exec()
259	\Odd set the size of the output vector passed to
260	pcre_exec() to dd (any number of digits)
261	\P pass the PCRE_PARTIAL option to pcre_exec()
262	\S output details of memory get/free calls during matching
263	\Z pass the PCRE_NOTEOL option to pcre_exec()
264	\? pass the PCRE_NO_UTF8_CHECK option to
265	pcre_exec()
266	\>dd start the match at offset dd (any number of digits);
267	this sets the startoffset argument for pcre_exec()
268
269	A backslash followed by anything else just escapes the anything else.
270	If the very last character is a backslash, it is ignored. This gives a
271	way of passing an empty line as data, since a real empty line termi-
272	nates the data input.
273
274	If \M is present, pcretest calls pcre_exec() several times, with dif-
275	ferent values in the match_limit field of the pcre_extra data struc-
276	ture, until it finds the minimum number that is needed for pcre_exec()
277	to complete. This number is a measure of the amount of recursion and
278	backtracking that takes place, and checking it out can be instructive.
279	For most simple matches, the number is quite small, but for patterns
280	with very large numbers of matching possibilities, it can become large
281	very quickly with increasing length of subject string.
282
283	When \O is used, the value specified may be higher or lower than the
284	size set by the -O command line option (or defaulted to 45); \O applies
285	only to the call of pcre_exec() for the line in which it appears.
286
287	If the /P modifier was present on the pattern, causing the POSIX wrap-
288	per API to be used, only \B and \Z have any effect, causing REG_NOTBOL
289	and REG_NOTEOL to be passed to regexec() respectively.
290
291	The use of \x{hh...} to represent UTF-8 characters is not dependent on
292	the use of the /8 modifier on the pattern. It is recognized always.
293	There may be any number of hexadecimal digits inside the braces. The
294	result is from one to six bytes, encoded according to the UTF-8 rules.
295
296
297	OUTPUT FROM PCRETEST
298
299	When a match succeeds, pcretest outputs the list of captured substrings
300	that pcre_exec() returns, starting with number 0 for the string that
301	matched the whole pattern. Otherwise, it outputs "No match" or "Partial
302	match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
303	TIAL, respectively, and otherwise the PCRE negative error number. Here
304	is an example of an interactive pcretest run.
305
306	$ pcretest
307	PCRE version 5.00 07-Sep-2004
308
309	re> /^abc(\d+)/
310	data> abc123
311	0: abc123
312	1: 123
313	data> xyz
314	No match
315
316	If the strings contain any non-printing characters, they are output as
317	\0x escapes, or as \x{...} escapes if the /8 modifier was present on
318	the pattern. If the pattern has the /+ modifier, the output for sub-
319	string 0 is followed by the the rest of the subject string, identified
320	by "0+" like this:
321
322	re> /cat/+
323	data> cataract
324	0: cat
325	0+ aract
326
327	If the pattern has the /g or /G modifier, the results of successive
328	matching attempts are output in sequence, like this:
329
330	re> /\Bi(\w\w)/g
331	data> Mississippi
332	0: iss
333	1: ss
334	0: iss
335	1: ss
336	0: ipp
337	1: pp
338
339	"No match" is output only if the first match attempt fails.
340
341	If any of the sequences \C, \G, or \L are present in a data line that
342	is successfully matched, the substrings extracted by the convenience
343	functions are output with C, G, or L after the string number instead of
344	a colon. This is in addition to the normal full list. The string length
345	(that is, the return from the extraction function) is given in paren-
346	theses after each string for \C and \G.
347
348	Note that while patterns can be continued over several lines (a plain
349	">" prompt is used for continuations), data lines may not. However new-
350	lines can be included in data by means of the \n escape.
351
352
353	CALLOUTS
354
355	If the pattern contains any callout requests, pcretest's callout func-
356	tion is called during matching. By default, it displays the callout
357	number, the start and current positions in the text at the callout
358	time, and the next pattern item to be tested. For example, the output
359
360	--->pqrabcdef
361	0 ^ ^ \d
362
363	indicates that callout number 0 occurred for a match attempt starting
364	at the fourth character of the subject string, when the pointer was at
365	the seventh character of the data, and when the next pattern item was
366	\d. Just one circumflex is output if the start and current positions
367	are the same.
368
369	Callouts numbered 255 are assumed to be automatic callouts, inserted as
370	a result of the /C pattern modifier. In this case, instead of showing
371	the callout number, the offset in the pattern, preceded by a plus, is
372	output. For example:
373
374	re> /\d?[A-E]\*/C
375	data> E*
376	--->E*
377	+0 ^ \d?
378	+3 ^ [A-E]
379	+8 ^^ \*
380	+10 ^ ^
381	0: E*
382
383	The callout function in pcretest returns zero (carry on matching) by
384	default, but you can use an \C item in a data line (as described above)
385	to change this.
386
387	Inserting callouts can be helpful when using pcretest to check compli-
388	cated regular expressions. For further information about callouts, see
389	the pcrecallout documentation.
390
391
392	SAVING AND RELOADING COMPILED PATTERNS
393
394	The facilities described in this section are not available when the
395	POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
396	ifier is specified.
397
398	When the POSIX interface is not in use, you can cause pcretest to write
399	a compiled pattern to a file, by following the modifiers with > and a
400	file name. For example:
401
402	/pattern/im >/some/file
403
404	See the pcreprecompile documentation for a discussion about saving and
405	re-using compiled patterns.
406
407	The data that is written is binary. The first eight bytes are the
408	length of the compiled pattern data followed by the length of the
409	optional study data, each written as four bytes in big-endian order
410	(most significant byte first). If there is no study data (either the
411	pattern was not studied, or studying did not return any data), the sec-
412	ond length is zero. The lengths are followed by an exact copy of the
413	compiled pattern. If there is additional study data, this follows imme-
414	diately after the compiled pattern. After writing the file, pcretest
415	expects to read a new pattern.
416
417	A saved pattern can be reloaded into pcretest by specifing < and a file
418	name instead of a pattern. The name of the file must not contain a <
419	character, as otherwise pcretest will interpret the line as a pattern
420	delimited by < characters. For example:
421
422	re> </some/file
423	Compiled regex loaded from /some/file
424	No study data
425
426	When the pattern has been loaded, pcretest proceeds to read data lines
427	in the usual way.
428
429	You can copy a file written by pcretest to a different host and reload
430	it there, even if the new host has opposite endianness to the one on
431	which the pattern was compiled. For example, you can compile on an i86
432	machine and run on a SPARC machine.
433
434	File names for saving and reloading can be absolute or relative, but
435	note that the shell facility of expanding a file name that starts with
436	a tilde (~) is not available.
437
438	The ability to save and reload files in pcretest is intended for test-
439	ing and experimentation. It is not intended for production use because
440	only a single pattern can be written to a file. Furthermore, there is
441	no facility for supplying custom character tables for use with a
442	reloaded pattern. If the original pattern was compiled with custom
443	tables, an attempt to match a subject string using a reloaded pattern
444	is likely to cause pcretest to crash. Finally, if you attempt to load
445	a file that is not in the correct format, the result is undefined.
446
447
448	AUTHOR
449
450	Philip Hazel <ph10@cam.ac.uk>
451	University Computing Service,
452	Cambridge CB2 3QG, England.
453
454	Last updated: 10 September 2004
455	Copyright (c) 1997-2004 University of Cambridge.